MTB front suspension systems still in production...

Some notes from my cluttered mind..

"Simon Brooke" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

I am, mainly for my own education and amusement, doing a little bit of research into MTB front
suspension systems.

The mainstream conventional system of course is the dual sliding stanchion fork with the sliders
at the bottom. I can remember from about thirty years ago a detailed technical article by a
British motoring journalist who wrote as LJK Setright (it may even have been his real name) on
motorcycle suspension in which I recall that he concluded, for apparently convincing reasons, that
for motorcycles anyway this was the worst possible design (mainly as I recall due to poor
stiffness).

There are several disadvantages to the dual stanchion fork: somewhat poorer stiffness, stiction,
brake dive to name a few.

Quoted message said:

Joe Murray and by Matt Lawwill(?sp) but I can't find any pictures of

His name was Mert Lawwill. He made the leader fork and it was a four leading link design. See photo
here bikepro.comlawill index.htmlOpen ↗.

Quoted message said:

I'm also aware of other 'sleeve at the top' dual stanchion designs in the past (Halston and
Suspenders) and another in-headtube designs (Action Tec).

'sleeve at the top' is referred to generally as "upside down forks". "Right way up" being the slider
on the bottom style.

Quoted message said:

Why did the equal-length-link fork die?

I'm not sure it's dead entirely..there might still be a few makers around.

Quoted message said:

Which of these designs do you consider better than the 'sleeve at the bottom' dual stanchion
design, and why?

I can't say for sure with bicycles, but in motorcycles, the dual stanchion design is still king.
There are some link design front suspensions (BMW and Honda both have them..) but racing bikes still
prefer the old-style forks. I believe they prefer the feel of those forks and the steering feel.
They actually LIKE the brake dive and accompanying geometry change as a method to get the bike to
turn in quickly but not be too steep during straight-line riding. I also suspect they are well
refined and understood better than the newer link designs.

Cheers,

Scott..

Simon Brooke <[email hidden]> wrote in message news:<[email hidden]>...

[snip]

Dear Simon,

The last picture that I can find of leading-link or springer forks in the observed trials world is
in the 1969 "Sammy Miller on Trials," where Gordon Jackson is shown plunging into a bog up to his
front hub on a Greeves Anglian.

About the same time, the dual-range gearbox Honda Trail 90 with leading link forks turned into a
110cc bike and switched to telescopic forks.

Apart from their exposed complexity, leading-link forks gave far less travel, as I recall. Off-road,
travel mattered far more than preserving precise steering geometry.

Since early mountain bikes probably imitated off-road motorcycles, they would have been unlikely to
adopt a discarded front suspension scheme.

As for the upside-down forks, one of their advantages, apart from stiffer upper parts, is that they
reduce unsprung weight--the smaller diameter lower tubes that the suspension has to move are
lighter, which is important in motorcycles, where the front wheel and its suspension outweigh an
entire road bicycle.

Carl Fogel

In article <[email hidden]>,

Carl Fogel said:

Simon Brooke <[email hidden]> wrote in message
news:<[email hidden]>...

[snip]

Dear Simon,

The last picture that I can find of leading-link or springer forks in the observed trials world is
in the 1969 "Sammy Miller on Trials," where Gordon Jackson is shown plunging into a bog up to his
front hub on a Greeves Anglian.

But the Greeves that won the Scottish Six Days in '69 ridden by Bill Wilkinson was using a Metal
Profile telescopic front fork.

Alternative front ends have appeared in the off-road motorcycle world occasionaly since then.
Roger Decoster raced an MX bike with a sprung girder front end that gave 13 inches of travel(!) in
the late 70s.

Modern MX bikes use about 11 inches of travel; more than that results in too much of a geometry
change. Modern trials motorcycles use about 7 inches. Trials motorcycles are getting very light; the
lightest (Gas Gas Adam Raga replica) is at 139 lbs. At the rate that trials bikes are getting
lighter and mountain bikes are getting heavier and more motorcycle-like I expect them to meet in
about three years. (actually its already happened; some french guy set a 125mph downhill speed
record in the mid 90s on a mountain bike built from a Yamaha TYZ trials bike chassis. The bike was
built by Bernie Schreiber, the only American world trials champion).

Eric

"Eric M" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

In article <[email hidden]>, Carl Fogel

Quoted message said:

Simon Brooke <[email hidden]> wrote in message
news:<[email hidden]>...

[snip]

Dear Simon,

The last picture that I can find of leading-link or springer forks in the observed trials world
is in the 1969 "Sammy Miller on Trials," where Gordon Jackson is shown plunging into a bog up to
his front hub on a Greeves Anglian.

But the Greeves that won the Scottish Six Days in '69 ridden by Bill Wilkinson was using a Metal
Profile telescopic front fork.

Alternative front ends have appeared in the off-road motorcycle world occasionaly since then.
Roger Decoster raced an MX bike with a sprung girder front end that gave 13 inches of travel(!) in
the late 70s.

Modern MX bikes use about 11 inches of travel; more than that results in too much of a geometry
change. Modern trials motorcycles use about 7 inches. Trials motorcycles are getting very light;
the lightest (Gas Gas Adam Raga replica) is at 139 lbs. At the rate that trials bikes are getting
lighter and mountain bikes are getting heavier and more motorcycle-like I expect them to meet in
about three years. (actually its already happened; some french guy set a 125mph downhill speed
record in the mid 90s on a mountain bike built from a Yamaha TYZ trials bike chassis. The bike was
built by Bernie Schreiber, the only American world trials champion).

Eric

Dear Eric,

Here's a Greeves site showing one the last of the leading-link fork Anglian monsters in action in
1967 in color:

home.earthlink.nethistory.htmOpen ↗

Next to it is a black-and-white of the 1967 Anglian with a telescopic fork, and above this is the
Greeves Scottish Trials 1962-1964 model, showing its leading link.

Here's Roger DeCoster's weird 1979 Ribi leading-link fork with its enormous travel allowed by its
peculiar design, something that might interest Simon Brooke:

off-road.comrememberOpen ↗

Note that there are links both behind and in front of the shock-absorber and coil-spring unit, said
links being hinged near the bottom as vaguely explained later.

The Ribi link-fork design is mentioned here:

eric-gorr.comfuture biketech.htmlOpen ↗

"The link forks were tested by Honda via Roger DeCoster and an engineer from Brazil named Ribi. The
Ribi forks consisted of aluminum extrusions designed for rigidity. A single shock was mounted via
conventional shock linkage, to the triple clamp. The forks were rising rate and worked like a
conventional fork in that they compressed when you apply the front brake. Older leading link forks
work opposite meaning that the front end extended when the front brake was applied. That was great
on down-hills but very scary in turns! The Ribi fork design never made it in mx but it was later
adapted for roadracing and used with great success on the Britten, a bike made in New Zealand."

Alas, I found nothing on the Britten web site about anything except telescopic forks.

Another web site has this description of the odd Ribi fork on a 1987 Honda, claiming that it was a
Belgian rather than a Brazilian design:

slack.netbikeshad.txtOpen ↗

"Honda RC370 "Ribi Fork" - Roger DeCoster rode this bike in several championship races; the exotic
fork design was purchased from a Belgian designer by Honda and made for the 500 class bike. It had
three separate sections that hinged, folding up as the wheel went through its travel. Last time I
saw it, it was on display in Honda's Dallas Zone office. I think only one or two were ever made."

All the pictures show one other leading-link drawback for trials bikes--the front fenders were
always mounted up high, an abomination that obscured the front tire.

Carl Fogel

"Simon Brooke" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

I am, mainly for my own education and amusement, doing a little bit of research into MTB front
suspension systems.

The mainstream conventional system of course is the dual sliding stanchion fork with the sliders
at the bottom. I can remember from about thirty years ago a detailed technical article by a
British motoring journalist who wrote as LJK Setright (it may even have been his real name) on
motorcycle suspension in which I recall that he concluded, for apparently convincing reasons, that
for motorcycles anyway this was the worst possible design (mainly as I recall due to poor
stiffness).

I can track down still in production

* Dual sliding stanchion with sleeves at the bottom (90% of the market)

* Dual sliding stanchion with sleeves at the top (Maverick)

* Unequal length leading link (Whyte)

* Monoblade sliding stanchion with the sleeve at the top (Cannondale)

* USE Sub - a monoblade with what may technically be a leading link, although the geometry appears
quite different from other leading links

* In head tube (Cannondale again).

I can't find anyone still marketing an equal-length-link fork, although I saw such a thing for
sale on eBay not long ago. I know AMP used to make one, and I know there were leading link forks
produced by Joe Murray and by Matt Lawwill(?sp) but I can't find any pictures of either so I don't
know whether the links were equal length.

I'm also aware of other 'sleeve at the top' dual stanchion designs in the past (Halston and
Suspenders) and another in-headtube designs (Action Tec).

What have I missed?

Why did the equal-length-link fork die?

Which of these designs do you consider better than the 'sleeve at the bottom' dual stanchion
design, and why?

--
[email hidden] (Simon Brooke) jasmine.org.uk~simonOpen ↗

'graveyards are full of indispensable people'

my only comment would be that the Cannondale ones aren't "sliding" systems. No bushings, all roller
bearings; but you knew that already....

as far as the bottom sliders are concerned, you also need to consider manufacturing route. one side
usually has the spring, the other the damper. for that reason, and the fact that the wheel needs to
stay square, i'd say the "disadvantages" of bottom slider are small.

regarding the main argument against bottom sliders, mass, these are, from what i can see, small
compared to sticktion. i've had a marzocci x2, psylo and fox talas. with the first two, you may have
been able to tell me that mass was a factor because the ride, while fine, was not perfect cornering
on loose terrain. you could have told me that reaction time of higher mass affected the wheels
ability to track the terrain. but riding the fox *crushes* that assumption. it is so far superior to
anything else i've ever ridden, while still being no lightweight, it seems to me that sticktion and
proper damping are the biggest factors. if fox are able to get both those factors right, and it
takes a bottom slider to do it, then i'm happy with the compromise!

jb

Simon Brooke said:

I am, mainly for my own education and amusement, doing a little bit of research into MTB front
suspension systems.

The mainstream conventional system of course is the dual sliding stanchion fork with the sliders
at the bottom. I can remember from about thirty years ago a detailed technical article by a
British motoring journalist who wrote as LJK Setright (it may even have been his real name) on
motorcycle suspension in which I recall that he concluded, for apparently convincing reasons, that
for motorcycles anyway this was the worst possible design (mainly as I recall due to poor
stiffness).

I can track down still in production

* Dual sliding stanchion with sleeves at the bottom (90% of the market)

* Dual sliding stanchion with sleeves at the top (Maverick)

* Unequal length leading link (Whyte)

* Monoblade sliding stanchion with the sleeve at the top (Cannondale)

* USE Sub - a monoblade with what may technically be a leading link, although the geometry appears
quite different from other leading links

* In head tube (Cannondale again).

I can't find anyone still marketing an equal-length-link fork, although I saw such a thing for
sale on eBay not long ago. I know AMP used to make one, and I know there were leading link forks
produced by Joe Murray and by Matt Lawwill(?sp) but I can't find any pictures of either so I don't
know whether the links were equal length.

I'm also aware of other 'sleeve at the top' dual stanchion designs in the past (Halston and
Suspenders) and another in-headtube designs (Action Tec).

What have I missed?

Why did the equal-length-link fork die?

Which of these designs do you consider better than the 'sleeve at the bottom' dual stanchion
design, and why?

NICHOLAS CHILDS said:

"Simon Brooke" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

I can track down still in production

* Dual sliding stanchion with sleeves at the bottom (90% of the market)

* Dual sliding stanchion with sleeves at the top (Maverick)

* Unequal length leading link (Whyte)

* Monoblade sliding stanchion with the sleeve at the top (Cannondale)

* USE Sub - a monoblade with what may technically be a leading link, although the geometry
appears quite different from other leading links

* In head tube (Cannondale again).

my only comment would be that the Cannondale ones aren't "sliding" systems. No bushings, all
roller bearings; but you knew that already....

Well, I ride a Lefty-equipped Cannondale myself, so yes I do know it runs on roller bearings... this
doesn't feel to me a fundamental difference. Do you disagree? Where both Cannondale systems differ
from the conventional is that the inner part is constrained from rotating in the outer, which might
be seen as a fundamental difference.

--
[email hidden] (Simon Brooke) jasmine.org.uk~simonOpen ↗ ;; Generally Not Used ;;
Except by Middle Aged Computer Scientists

"Simon Brooke" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

NICHOLAS CHILDS said:

"Simon Brooke" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

I can track down still in production

* Dual sliding stanchion with sleeves at the bottom (90% of the

market)

Quoted message said:

Quoted message said:

Quoted message said:

* Dual sliding stanchion with sleeves at the top (Maverick)

* Unequal length leading link (Whyte)

* Monoblade sliding stanchion with the sleeve at the top (Cannondale)

* USE Sub - a monoblade with what may technically be a leading link, although the geometry
appears quite different from other leading links

* In head tube (Cannondale again).

Quoted message said:

Quoted message said:

my only comment would be that the Cannondale ones aren't "sliding"

systems.

Quoted message said:

Quoted message said:

No bushings, all roller bearings; but you knew that already....

Quoted message said:

Well, I ride a Lefty-equipped Cannondale myself, so yes I do know it runs on roller bearings...
this doesn't feel to me a fundamental difference. Do you disagree? Where both Cannondale systems
differ from the conventional is that the inner part is constrained from rotating in the outer,
which might be seen as a fundamental difference.

I think the removal of stiction is important and while Lefty's and Headshoks have been tested to
have less flex it's hard to determine whether this is due only to the use of roller bearings or
better engineered materials overall. 'Shocks' aren't that complicated - spring, damper, and relative
movement system(telescoping, linkage, etc.). Do any motorcycle manufacturers use roller bearings?
Perhaps the use of larger diameter stanchions minimises stiction and flex for a lower weight
penalty? Maybe the bushings are replaceable?

Nick